Rendering a large number of unique objects
You could group all the brains (Ctrl-G) and then use the brain group in a particle system on a grid which emits from each vertex. Make sure the number of vertices = number of particles. Also be sure to display your models as bounds only, otherwise Blender will try to draw all the detail in viewport. Using a particle system allows me to draw forests of complex trees, so I think brains should work too.

In the picture you see the group of objects in the front and the result of a particle system on a subdivided grid emitting from each vertex in the background.